Method of coating electrical conductors



l ,LI /ff u. n Z .Ar WIJ R. C HARTSOUGH Original Filed Dec.

\IL\IL METHOD OF COATING ELECTRICAL CONDUCTORS .Al a: *w./^wvu Sept. 8, 1931.

Patented Sept. 8, 1931 UNITED STATESV PATENT OFFICE RALPH CLAYTON HARTSOUGH, OF BERWYN, ILLINOIS, .ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A. CORPORATION OF NEW YORK METHOD OF COATING ELECTRICAL CONDUCTORS Application led December 16, 1926, Serial No. 155,164. Renewed February 1B, 1931.

This invention relates to methods of coating electrical conductors, and more particularly to methods of baking a coating of insulating enamel upon a wire.

` 5 In the process of coating a w1re with insulating enam'el, it is the practice in some instances to pass the wire through a bath of suitable coating composition and subsequently subject the applied coating to heat, thereby vaporizing the volatile portions of the composition and baking the residual portion upon the wire. Minute or microscopic openings have, in some instances, been found to be present in the baked coating and it is believed that these are formed as a result of solvents breaking out in minute bubbles during the vaporization thereof. These openings or holes in the insulating enamel being microscopic in size, do not impair the insulating properties of the coating.

The primary object of this invention is to provide a simple and eiiicient method of economically and expeditiously baking a coating on electrical conductors.

In order to obtain these and Vother objects and in accordance with the general features of the invention, one embodiment thereof includes a means for continuously passing a wire through a bath of insulating material. The wire, prior to its entrance into the insulating material, is passed over a pulley which forms one terminal of a source of electrical current supply and subsequent to this coating operation the wire is passed through a bath of current conducting Huid material, such as mercury, which forms the other terminal of the source of electrical current supply. The mercury temporarily enters the microscopic openings in the coating resulting from the baking operation and contacts with the Wire, thereby including an everchanging wire portion of constant extent Within an electrical circuit, the current passing therethrough serving to heat the wire and thereby continuously bake the applied insulating coating und the coated Wire is then passed from the conducting Huid to a suitable wire receiving spool.

These and other objects will be apparent from the following detailed description and the accompanying drawing illustrating one embodiment of the invention in an'apparatus by means of which the method may be practiced and in which is shown a fragmentary side elevational view, partially in section, of a wire-insulating apparatus, a circuit diagram mcluding a source of low frequency current supply being shown in association therewith.

Referring now to the drawing, it will be observed that a wire spool 10 is carried by a bracket secured on the side of a suitable machine frame 11. A wire 13 from the supply spool 10 passes downwardly over a metallic pulley 14 which is mounted upon a bracket 16 secured to the machine frame 11 and electrically insulated from the bracket by means of an insulating bushing 17. From the pulley 14 the wire is directed downwardly into a bath of insulating material 19 of any suitable character within a suitable container 20 and is guided therethrough by means of a pulley or sheave 21 rotatably mounted within the container. After passing through the bath 19 the wire is directed upwardly through a heating chamber 22 and passes over a pulley or sheave 23 which is supported by the upper end of a vertical bracket 24 suitably mounted upon the upper portion of the machine frame 11. The wire is then fed downwardly from this sheave 23 to a sheave (not'shown) companion to and in alignment with the sheave 21 and then upwardly over an idler pulley 25. From the pulley 25 the wire is passed downwardly through a bath of mercury 26 or other suitable electrical conducting fluid material to an idler pulley or sheave 27 rotatably mounted within a fluid container 28 -and then upwardly to an idler pulley 29 from which pulley the coated wire is led to a suitable receiving spool 30. This receiving spool 30 may be driven from any suitable source of power (not shown), the speed of the spool being regulated to the speed at which it is desired to feed the wire upwardly through the heating chamber 22.

It will be observed that the mercury bath or electrode 26 and the metallic pulley 14 form opposite terminals of an electrical circuit which includes a suitable source of low frequency electrical current supply 32, a switch 33, a transformer 34, a switch 35 and `an adjustable resistance 36. The circuit including the secondary winding of the transformer 34 may be traced in part from a spring brush 38 engaging with a hub on the pulley 14 through the secondary winding of the transformer 34, the switch 35, the adjustable resistance 36 and thence to a. terminal 39 positioned within the lower portion of the mercury bath 26.

When the coated wire from the idler pulley 25 is introduced into the mercury 26, microscopic pores or openings in the coating resulting from the baking thereof permit the mercury to make directcontact through the coating with the wire conductor. As the coated wire is directed upwardly away from the mercury bath the mercury within the microscopic openings dislodges itself therefrom and hence the coating of the wire received by the spool 30 is free from mercury content. The contacting of the mercury with the wire serves to complete the secondary circuit. above described, by establishing an electrical connection between the metallic pulley 14 and the body of mercury 26 through the portion of wire 13 extending therebetween. From the foregoing it will be clear that when the switches 33 and 35 are closed and the electrical circuit is completed through the wire 13. as described, current will flow therethrough and bv proper adjustment of the resistance 36. the heat generated thereby within that portion of the wire may serveto effectively bake the coating of insulating enamel previously applied to that portion. In this connection it is to be under- -stood that a plurality of sheaves similar to the sheaves 21 and 23 might be employed, the number of sheaves being dependent upon the number of times it is desired to pass the wire through the coating compound and through the chamber Q2 before passincr it through the mercury bath or electrode 26.

By the practice of this improved method an electrical heating current mav be passed through successive. ever-changing portions of a coated wire of uniform length` this length being determined b v the ext-ent of wire reaching between the mercury 26 and the metallic pulley 14. In the disclosure. a source of low frequency current siipplv 32 has been shown, but it will be understood that direct or high frequency current could be employed with equal effectiveness. By utilizing the minute openings which are present in the baked enamel, as above described, direct contact with the wire conductor may be effected through this intact enamel coating without any alterations thereof, thereby greatly facilitating the baking of the coating by the passage of a low frequency current through an ever-changing constant portion of the Wire.

It is to be understood that the invention is not limited to the exact con-struction and functional characteristics herein described and that the appended claims have been drawn to define other modifications which come within the true spirit and scope of the invention.

What is claimed is:

1. The method of insulating an electrical conductor, which consists in coating the conductor, and then making a direct contact with the conductor through the coating thereof with an electrically conducting liquid eleclrode to connect the conductor with a source of electrical current supply, thereby heating the conductor to bake the coating.

2. The method of insulating an electrical conductor, which consists in coating the conductor, directly contacting one terminal of a source of electrical current supply with an uncoated portion of the conductor, and then directly contacting an electrically conducting liquid body forming the other terminal of the source of current supply with the conductor, thereby heating the conductor to bake the coating.

3. The method of insulating an electrical conductor, which consists in coating the conductor, and then making a direct contact with the conductor through a portion of intact coating to connect the conductor with a source of electrical current supply, thereby heating the conductor to bake the coating.

4. The method of insulating an electrical conductor, which consists in coating the conductor, contacting the conductor with an electrically conducting liquid electrode of a source of electrical current supply through a restricted opening in the conductor coating to connect the conductor with the source of current supply, thereby heating the conductor to bake the coating.

5. The method of insulating an electrical conductor, which consists in coating the conductor, forming an opening in the coating by baking, and utilizing the opening for establishing a direct contact with the conductor to connect the conductor with a source of electrical current supply, thereby causing the continuous baking of the coating on the poriion of the conductor through which the current passes.

6. The method of insulating an electrical conductor, which consists in coating the conductor with material which is formed with microscopic openings upon being baked, directly contacting with one terminal of a source of electrical current supply with an imcoated portion of the conductor, and then passing the coated conductor through a body of elecrically conducting liquidY material which forms the other terminal of the source of current supply to cause a heating current RALPH CLAYTON HARTSOUGH. 

